The Next-Generation Layered Hydroxide Electrocatalysts Based on High-Entropy Strategy: Synthesis, Characterization, and Electrochemical Applications

High-entropy layered hydroxides (HE-LHs) with five or more metal elements have drawn great attention because of their unique properties and scalable synthesis. Equipped with a tunable interlayer of two-dimensional infrastructure, considerable atomic diversity, and promising industrial applications. These HE-LHs have significantly higher mixed entropy and more complicated multiorbital hybrid effects than conventional hydroxides, which allows them to gain a customizable catalytic microenvironment, ideal conductivity, and thermodynamic stability. Although the high-entropy strategy has been widely discussed in alloy and oxide systems, its immense potential in layered hydroxides remains undervalued. This review provides a comprehensive summary of the latest progress of layered hydroxides modified with the high-entropy strategy, from the synthetic methods to electrochemical applications. The versatile synthetic strategies, including hydrothermal reaction, solvothermal reaction, co-precipitation, and electrodeposition methods, are summarized. Besides, a thorough discussion of characterization methods for analyzing the basic structure of HE-LHs is given and their electrochemical performance is assessed. Ultimately, this review briefly outlines the application of HE-LHs in fields of oxygen evolution reaction, hydrogen evolution reaction, organic-molecular oxidation reaction, and supercapacitors. This review provides a reliable reference for synthesizing and evaluating HE-LHs, thus highlighting the giant potential of HE-LHs and prompting the next generation of layered hydroxides.